1. Field of the Invention
This invention relates to pressure transducers and more particularly a transducer utilizing strain gauges on diametric opposite sides of a slender column or collapsible pin to measure force by the bending of the slender column collapsible pin prior to a critical force at which the slender column would collapse. Rupture pin pressure relief valves are generally well known. A collapsible or buckling pin is formed by a slender column which yields or collapses by force applied to the axis of the slender column. The yield point at which the column collapses can be easily calibrated in accordance with Euler's formula for slender columns.
Transducers for indicating the value of a force or pressure are well known. Such transducers generally include a diaphragm and strain gauges on the diaphragm indicates the pressure value by diaphragm fluctuation. Instruments recording such fluctuations must be periodically adjusted to achieve accuracy in measurement. As stated hereinabove this invention uses strain gauges on opposite sides of a slender column with the force to be measured axially impressed on the slender column.
This invention is an improvement over known force transducers by using a collapsible pin having opposing parallel sides so that the direction of bending of the collapsible pin under axial pressure below its yield value will be known by bending laterally in either its flat surfaces direction. Since the direction of bending is known, the amount of bending can be measured.
2. Description of the Prior Art
U.S. Pat. No. 5,146,942 issued Sep. 15, 1992 to Taylor for Low Pressure Fluid Emergency Shutdown Valve and U.S. Pat. No. 5,297,575 issued Mar. 29, 1994 for In-Line High Pressure Fluid Release Valve are believed good examples of the state-of-the-art. Each of these patents disclose a long slender column forming a pressure collapsible pin having one end portion secured in a socket of a valve body and the opposite end portion of the pin secured in a coaxial socket moved toward the axis of the collapsible pin by fluid pressure in a vessel or line being monitored. The collapsible pin being responsive to the axially imposed force caused by fluid pressure will swing laterally and buckle in response to fluid pressure greater the yield value of the slender pin. The direction of bending is not known since it is free to bend in any direction.